The funny thing is that i have only been to 3 sf parks, 2 of them are no longer (SFWoA and Astroworld).  I have been to both companies flagship parks.  And one park that was controlled by both companies (Geauga Lake).  It is hard to judge a company from their past experiences.  Plus I am tainted being from Cleveland, OH.  When you have Cedar Point in your backyard, kinda tough not being biased.   
  
I see good stuff happening by both companies.  I hope SF operations have gotten better since my last visit to SFMM 6 years ago.  Truthfully, I need to do a coaster trip next year to give my opinion.  But right now, I lean Cedar Fair.